1. Field of the Invention
The present general inventive concept generally relates to a power supply device and an image forming apparatus having the same, and more particularly, to a power supply device which senses whether power has been supplied to an image forming apparatus, through low power consumption, and an image forming apparatus having the same.
2. Description of the Related Art
An image forming apparatus is an apparatus which generates, prints, transmits, etc. image data. Examples of the image forming apparatus include a printer, a scanner, a copier, a fax machine, and a multifunction peripheral (MFP) having combined functions thereof.
The image forming apparatus requires information about whether power (in detail, alternating current (AC) power) is being supplied thereto. In detail, the image forming apparatus includes an energy storage device having a large capacity. Therefore, although external power is temporarily cut off, a system is not immediately turned off. As a result, if a user unplugs an AC power cord and then immediately plugs the AC power cord in to stop a printing job, data stored in a memory is maintained, thereby causing unnecessary printing.
In this point, the image forming apparatus senses whether power is being supplied thereto. If it is sensed that the power is cut off, the image forming apparatus immediately deletes data from the memory.
The image forming apparatus uses a photo-coupler to sense whether power is supplied. In this case, it is difficult to maintain power consumption to 1 W or less in a standby mode.
In detail, the photo-coupler biases a predetermined current to transmit a signal, and thus a large amount of power consumption (about 0.2 W) occurs. This power consumption gives high weight to achieve 1 W in a standby mode.